Any creative ideas for shortening a Crankshaft?

Long story short, I have to shave about 2.5mm off the end of the crankshaft of our Honda clones (rental karts)

Looking for ideas on how to do this neatly while the engine is assembled. Really don’t think we’ll have time to pull apart 12 engines and put the cranks in a lathe on top of everything else going on.

Someone had a go at this one and the results are not stellar lol.

That’s what you get for using a cowboy as a machinist!

You are staring at a powerful lathe right there. Clamp a tool holder to the frame so that you can feed the tool right in perpendicular to the crankshaft’s axis of rotation, rev the engine up, and feed it in. There are safer methods, but that would be fastest.

The next best way is to just have someone who is skilled with a hacksaw cut it off. Use a real hacksaw blade, not one made from bubblegum, not one with three teeth per inch for wood.

After that we’re down to using an air powered cutoff wheel or die grinder to obliterate enough metal to get the required clearance.

Crank is hardened so the only safe way to do this with engine assembled is with an angle grinder, high speed and and good cutting discs. That’s what we used to cut the Vespa cranks back in the days, works like a charm. You can slip a bigger piece of thick tubing on the outside to act as a guide: as you are cutting down you will have a reference point to run against or at least parallel to